Chain joint assembly and a method for the manufacture thereof

ABSTRACT

A chain with mutually connected chain links ( 1, 2 ) each comprising a back portion and two parallel wall portions protruding substantially perpendicularly therefrom, in which wall portions corresponding rivet holes have been provided in each of the two and members of the chain link, wherein the chain links ( 1, 2 ) are connected with one another by means of an end member of a chain link with a comparatively narrow ( 2 ) back portion which is inserted into an end member of a neighbouring chain link with a comparatively broad back portion ( 1 ) such that the rivet holes ( 1   c   , 2   c ) in the parallel wall portions of the two end members ( 1   a   , 1   b   ,2   a   -2   b ) are positioned opposite one another for engaging a river ( 3 ) or a shaft member. By use of rivets or shaft members of such a length that the rivet ( 3 ) may be axially retained by deformation of areas of said wall portions ( 1   a   -1   b ) around the rivet holes ( 1   c ) from the exterior side for reducing the clear opening of the rivet holes, a chain is produced by use of less material and at subsequently reduced costs relative to chains hitherto known.

The present invention relates to a chain and a method for themanufacture of a chain by riveting, said chain consisting of mutuallyconnected chain links, each comprising a back portion and two parallelwall portions protruding substantially perpendicularly therefrom, inwhich wall portions corresponding rivet holes have been provided in eachof the two end members of the chain link, wherein the chain links areconnected with one another by means of an end member of a chain linkwith a comparatively narrow back portion which is inserted into an endmember of a neighbouring chain link with a comparatively broad backportion such that the rivet holes in the parallel wall portions of thetwo end members are positioned opposite one another for engaging a rivetor a shaft member.

It is known from U.S. Pat. No. 3,302,288 to manufacture chains byriveting, the ends of the rivet being deformed such that the rivet isretained in the axial direction.

It is a drawback of this prior art that comparatively long rivets haveto be used, said rivets protruding beyond said parallel wall portions inthe broad chain links, or the heads thereof subsequently having to bepressed into the wall portions, and, consequently, fairly much materialis to be used for these rivets. At the same time, it is in severalconnections a disadvantage that the exterior of such a chain is notsmooth, or that the chain links are substantially broader thannecessary.

DE A1 197 05 019 discloses a chain with alternating broad and narrowchain links which are pivotally connected with hinge pins inserted intoholes in the chain links. The ends of the hinge pins are flush with theexterior sides of the broad chain links and are welded thereto. In analternative embodiment no holes are provided in the broad chain links,and the hinge pins are welded to the interior side of the broad chainlinks.

From DE 26 22 602 B2 a chain is likewise known, in which hinge pins arewelded onto the side members.

It is a drawback of this prior art that welding is used for retainingthe hinge pins in axial direction, as this from a technical point ofview is difficult and costly in manufacture.

An object of the invention is to provide a chain and a method for themanufacture of chains by riveting, which chains do not suffer from theabove drawbacks.

This object is met by means of a chain which is characterized in thatthe rivet or the shaft member has such length that the rivet may beaxially retained by deformation of areas of said wall portions aroundthe rivet holes from the exterior side for reducing the clear opening ofthe rivet holes.

The invention will now be explained in detail in the following withreference to the schematic drawing, in which

FIG. 1 is a perspective view of a chain link according to the invention,seen obliquely from below,

FIG. 2 is a longitudinal sectional view of a chain link duringmanufacture,

FIG. 3 a view of a chain link with identical links, and

FIG. 4 wall portions with bores around the rivet holes.

In FIG. 1 a broad chain link 1 is shown with parallel wall portions 1 aand 1 b and a narrow chain link 2 with parallel wall portions 2 a and 2b. The narrow chain link 2 is inserted between the parallel wallportions 1 a and 1 b of the broad chain link 1.

FIG. 2 shows how a rivet 3 of shorter length than the distance D betweenthe exterior sides of the wall portions 1 a-1 b of the broad chain link1 has been inserted through aligned rivet holes 1 c, 2 c, respectively,in the wall portions 1 a-1 b and 2 a-2 b. Subsequently, the wallportions 1 a-1 b of the broad chain link 1 is deformed from the exteriorside, edge portions around the rivet holes 1 c being depressed forreducing the clear opening of the rivet holes and for retaining therivet in axial direction. The deformation may be made by impact or anyother ordinary type of deformation technique, for instance embossing, onthe wall portion 1 a of the broad chain link with an embossing head 4,the wall portion 1 b being in abutment against a correspondingstationary embossing head 5.

The deformation may advantageously be made with an embossing headprovided with a number of pointed, arched segments consisting of twoembossing surfaces. The first embossing surface of the embossing head atits biggest radius may advantageously be designed as a surface whichduring the embossing is substantially perpendicular to the exterior sideof the wall portions 1 a-1 b. The second embossing surface of theembossing head may advantageously be designed as a surface which duringthe embossing forms an angle of for instance 45° C. with the exteriorside of the wall portions 1 a-1 b. Another possibility would be tomanufacture the embossing head as a circular segment.

The chain link shown in FIG. 3 is an alternative embodiment, in whichthe chain links have a narrow and a broad end, all chain links beingthus identical.

FIG. 4 shows an alternative to deformation of the edge areas, where, inthe wall portion in the immediate vicinity of the rivet holes,depressions or throughgoing holes are provided, for instance in the formof an arch or of a circular form, which holes for instance by use of asuitable mandrel may be used for reduction of the clear opening of therivet holes and thus result in a compression around the rivet.

The rivet may have such a length that it only just reaches from one wallportion to the second one, or it may be so broad that it reaches fromthe exterior side of one wall portion to the exterior side of the secondwall portion. Another possible embodiment of the rivet would be toprovide it, irrespective of its length, with a chamfer or the like atits end faces in order to ensure sufficient space for the materialsurplus resulting from the deformation of the wall portion of the chainlink.

What is claimed is:
 1. A chain comprising a plurality of chain links andrivets, each chain link having a back portion and two parallel wallportions extending at substantially right angles from the back portion,said wall portions having substantially flat exterior sides, whereineach chain link has end portions having portions of the parallel wallportions and rivet holes, wherein the end portions of each chain linkoverlap end portions of adjacent chain links to form a connection, oneof the overlapping end portions of each connection defining an inner endportion and the other of the overlapping end portions of each connectiondefining an outer end portion, wherein the rivet holes of theoverlapping end portions of each connection are in alignment with oneanother, wherein one of the rivets is positioned in the aligned rivetholes of the overlapping end portions of each connection, said rivethaving a length not exceeding a distance between the exterior sides ofthe outer end portions of the parallel wall portions, whereindeformations of areas of the wall portions of the outer end portion ofeach connection adjacent the rivet holes of the outer end portion narrowthe rivet holes of the outer end portion and axially retain the rivet.2. A chain according to claim 1, wherein the chain comprises a pluralityof first chain links alternating with a plurality of second chain links,the end portions of each first chain link being narrower than the endportions of each second chain link.
 3. A chain according to claim 1,wherein each chain link has a first end portion and a second end portionnarrower than the first end portion, the first end portion forming theouter end portion of each connection, and the second end portion formingthe inner end portion of each connection.
 4. A method for themanufacture of a chain, comprising the steps of: providing chain linkseach comprising a back portion, two parallel wall portions extending atsubstantially right angles from the back portion, and end portions withrivet holes, the wall portions having substantially flat exterior sides,overlapping the end portions of adjacent chain links to form connectionssuch that the rivet holes of overlapping end portions are aligned, theoverlapping end portions of each connection forming an outer end portionand an inner end portion, providing for each connection a rivet having alength not exceeding a distance between said exterior sides of the outerend portion, inserting the rivet through aligned rivet holes of theoverlapping end portions of adjacent chain links at each connection, anddeforming areas of the outer end portion adjacent the rivet holes of theouter end portion at each connection to reduce the rivet holes toaxially retain the rivet.
 5. A method according to claim 4, wherein thedeforming step includes impacting the outer end members of one of theparallel wall portions at each connection with an embossing head, theouter end member of the other parallel wall portion at each connectionbeing brought into abutment on a stationary embossing head.